Assessing flood hazards and evacuation safety in metro stations: insights from Paral·lel station (Barcelona)

Abstract The increasing frequency of extreme rainfall events due to climate change has heightened flood risks in underground transport systems. Metro stations, particularly concourses and staircases, are highly vulnerable, posing severe threats to passenger safety. This study assesses flood hazards in the Nou de la Rambla concourse of Paral·lel metro station (Barcelona) using a high-resolution two-dimensional hydraulic model developed with Iber software and calibrated with site-specific topographic data and historical observations. Four inflow scenarios (0.2, 0.4, 0.6 and 0.8 m 3 /s) were simulated to evaluate water depth, flow velocity, and evacuation feasibility based on three hazard indicators: specific force per unit width (SFPUW, M 0 ), critical velocity, and the depth–velocity product. The results indicate that flooding primarily affects station entrances and evacuation paths, where steep slopes and confined geometries amplify flow hazards. Pedestrian stability is especially compromised on access staircases and ramps. Hazard maps identify zones where pedestrian stability is most compromised, supporting targeted emergency response planning. This study advances previous research by applying human-centred flood hazard criteria in a real underground metro environment. The results underscore the importance of integrating hydraulic modelling with pedestrian safety assessment to support hazard-informed adaptation strategies for flood-resilient metro infrastructure.